INVESTIGADORES
LLERA Andrea Sabina
artículos
Título:
Crystal Structure of Imaginal Disc Growth Factor 2: a Member of a New Family of Growth Promoting Glycoproteins form Drosophila Melanogaster
Autor/es:
FERNANDEZ VARELA, P; LLERA ANDREA S; MARIUZZA, R; TORMO, J
Revista:
JOURNAL OF BIOLOGICAL CHEMISTRY
Referencias:
Año: 2002 vol. 277 p. 13229 - 13236
ISSN:
0021-9258
Resumen:
Imaginal disc growth factor-2 (IDGF-2) is a member
of
a recently described family of Drosophila
melanogastersoluble
polypeptide growth factors that promote cell
proliferation in imaginal discs. Although their
precise
mode of action has not been established, IDGFs
cooperate
with insulin in stimulating the growth of imaginal
disc cells. We report the crystal structure of
IDGF-2 at
1.3-Å resolution. The structure shows the classical
(__)8
barrel-fold of family 18 glycosyl hydrolases, with
an insertion
of an _ _ _ domain similar to that of Serratia
marcescens chitinases A and B. However, amino acid
substitutions in the consensus catalytic sequence of
chitinases give IDGF-2 a less negatively charged
environment
in its putative ligand-binding site and preclude
the nucleophilic attack mechanism of chitin
hydrolysis.
Particularly important is the replacement of Glu by
Gln
at position 132, which has been shown to abolish
enzymatic
activity in chitinases. Nevertheless, a modest
conservation
of residues that participate in oligosaccharide
recognition suggests that IDGF-2 could bind
carbohydrates,
assuming several conformational changes to
open the partially occluded binding site. Thus,
IDGFs
may have evolved from chitinases to acquire new
functions
as growth factors, interacting with cell surface
glycoproteins implicated in growth-promoting
processes,
such as the Drosophila insulin receptor.